Process of leaching copper ores.



"40 gentle nnirnn STATES PATENT GFFICE.

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- 'To all whom it may concern:

' Be known that I, GEORG CL ENS SCHNEIDER, mining councillor, chief of the Royal Metallurgical Laboratory, a sub'ect of 5 the German Emperor, and resident o ,Freiberg, Germany. with the post-office address 'Parkstrasse No. 300, have invented new and useful Improvements in Processes of Leaching Copper Ores, of which the following is a .-"-;pecification.

Up to the present no method exists of profitably leaching calcereous low grade copper ores either consisting of oxide alone or of oxids and sulfide of that metal. The

ordinary acid process of extraction is far too unprofitable, and the same applies to the use of salts of iron, and other methods. -Horeover, the repeatedly advocated and investigated extraction with ammonia and ammonia salts has no prospect of success in practice, even if only from the fact that the apparatus is very large, c mplicate'cl and expensive when anything li e a large quantity has to be treated. I

It has now been ascertained that even a dilute solution of potassiumhydroxid or sodium hydroxid is suflicient to convert the natural carbonates of copper malachite and azurite) into copper hydroxid. This hydroxid, however, is'well known to be soluble in various organic substances, such foriex- 'a-m le as tartrates, grape sugar, saccharose y'ian glycerin. Hence t e copper can be extracted from copper car onate ores-by treating the same'wi'th a dilute solution or one of these organic substances in presence of caustic soda; and if the ores'be crushed s'ufliciently fine the process ofsolution'wih g on even in the cold, though it is accelerat gd by the application or heat (a temperature of In this operation tartra-tes, dissolve a little lime as well, though not much; sugar exhibits a slightly diminished solvent power, while glycerin has proved to be the most suitable, as also with regard to the regenera-.

tion of the liquors. Thusfor example, a solution of 10 kilos of caustic soda and 10 liters glycerin in 100 liters of water, is found to extract approximately 66 kilos of a lowgrade copper oxid ore containing 2.75% of copper and about 20% of carbonates of lime and magnesia, in aboutS hours at; 50C. to

Specification of Letters Patent. Patented Aug. 31, 1909. Application filed February 4, 190a. Serial 110.4%,074.

, such an extent that only 04-05% of copper is left behind, while none of the lime or magnesia passes into solution. Calcined cupric oxid is also soluble in this liquid and consequently so are malachite, azurite and'red copper ore that have been converted into cupric oxid by heating. The same applies to copper sulfid roasted at dull red heat. Hence, after a short preliminary roasting evencalcareous ores can be extracted that contain red copper ore, copper glance, copper pyrites or variegated copper ore, either alone or in resence of malachite or azurite, particular y since both lime and ferric oxids are insoluble in the liquor.

The recovery of copper from the liquor is most cheaply and suitably effected by elecis obtained on the cathodes, and is invariably accompanied by the precipitation of cuprous oxid equivalent to about 10% of thecopper. Both can be smelted in presence of a small amount of coal, and after a brief process of fining can be run into molds.

' y The regeneration of the solution which contains a quantity of sodium carbonate corresponding with the carbon dioxld' contents of the copper carbonate, is effected by the 'trolysis and not by special chemical reagents. Y By these means a copper rich in Icupric oxid other hand no lime then dpasses into solution.

Now whatI claim an desire to secure by Letters Patent is the following:

1. A process for leaching calcareous cop-' per ores which consists in t-reatin the sand ores with a solution of caustic alkai, in presence of organic substances that are capable of dissolving cupric hydroxid substantially as described.

2. A process for leaching copper ores which consists in treating the said o'r'es after a previous roasting with a solution of caustic alkali in presence of organic substances that are capable offfldissolving cupric hydroxid substantially as described.

3. A process for leaching copper ores which dealn.

consists in treating the siiid ore with a di- In testimony, that I claim the. foregoing lute solution of caustic soda in presence of as my invention, I have signed 'niy name in 10 glycerin substantially asdesciribed- I presence ofitwo witnesses, this 19th day of 4. A process for leaching copper ores which J an'uf y, 1

5 consists in'treating approximately 66 kilos GEORG CLEMENS SCHNEIDER.

of said ores with a solution ofa-bout 10 kilos l Witnesses': c caustic soda, 10 liters glycerin and 100 liters FRIEDRICH KOLBEOK, Wa'tcnsubstentially as described. I I V MAR IN HENGLEIN. 

